"We do not require respect, only obedience."
Many of the Overseers possess wings, either natural ones made of feathers or mechanical ones awarded to an Overseer upon performance of a great deed. The Overseers' main weapon is the Lightcaster, a gun that usually takes on the form of a pistol. Clad in aerodynamic suits and often bearing floating halos, the Overseers are a powerful presence on the battlefield. They can also use vast amounts of energy to purge large areas of life.
The Overseers were initially reluctant to intervene in the dimensions of Infinity Wars. Their purpose was to watch, not act, and to fight the demons of Torment rather than the denizens of the planes. However, with the rise of the Virus of Avarrach and the unstoppable spread of the Sleepers, the extinction-level threat to their food source (humans) forced their hand. When the Prophet Karani sacrificed herself to open a gate between the Old World and Solace, the Overseers poured through and into the mortal realms.
Considering the Old World to be too infested and full of worthless beasts anyway, the Overseers purged the vast majority of the plane of all life, destroying not just the Sleepers but also much of the Warpath. Afterwards they proceeded to the other planes and began to systematically exterminate the Sleepers on the ground with the help of the Flame Dawn, Genesis Industries, and Descendants of the Dragon. Lilariah, a Champion of the Overseers, even imparted some of their power to three individuals: Kali, Lucca, and Xi. Soon the Sleepers were thought to be completely wiped out.
In Reish, the Overseers came into contact with Vasir, the Demon Prince of Torment who had been enslaved by the Cult of Verore. Following his escape from the Cult he engaged in an inconclusive skirmish with the Overseers. He and the demon Nysrugh are still at large and are currently associated with the Exiles. At this time, the Overseers imparted some of their power to Gao Han of the Descendants of the Dragon.
On Talich, the Overseers became closely allied with the Flame Dawn and Aberion. Upon finding out that Orion of the Genesis Industries was studying the Virus, the Overseers feared that he would attempt to weaponize it. The Overseers were not concerned with understanding the Virus; they merely sought to wipe it out. As such, they demanded that Orion destroy his samples, and when he refused they and the Flame Dawn declared war upon Genesis. Sol, a prominent Champion of the Overseers, personally slew Orion during one of the opening battles of this war which continues to rage.
No longer reluctant, the Overseers are becoming more and more involved with the affairs of the mortal planes. They have begun to regulate and investigate the rifts between worlds, questioning and even imprisoning any who had contact with them. They are aided in this oppression by the Flame Dawn, but as a result of their actions have become far less popular among many denizens of the multiverse. Xi departed their ranks and returned to her people, as did Lucca, reflecting a loss of mortal confidence and trust in the Overseers' actions.
With the Rebellion, it seems like every faction has at least in part turned against the Overseers' policies, made all the worse by the civil war withing Solace itself. Lilariah, doubting Sol's methods and sanity as he began to crack down harder and harder upon the mortal planes, gathered a group of like-minded angels and brought war to Solace, challenging the Champion of Vengeance's leadership.